Energy Harvesting Set to Accelerate IoT and IIoT Use Cases

How Energy Harvesting Frees IoT from the Grid

Image Source: Stock Spectrum/stock.adobe.com; generated with AI

By Robert Huntley for Mouser Electronics

Published June 13, 2025

Energy harvesting is a well-known technique that powers small Internet of Things (IoT) devices and nodes by transforming motion, temperature gradients, and even ambient radio frequency (RF) into minute amounts of power. New technologies allow engineers to use previously dismissed energy sources for the next generation of devices. This article dives into how energy harvesting from these sources can enable new IoT and Industrial IoT (IIoT) applications.

IoT and IIoT Go Mainstream

The advent of IoT has profoundly impacted our everyday lives. The ability to closely monitor and regulate every aspect of an industrial process heralds a new era of efficiency and overall operational effectiveness. Our homes and offices also benefit from IoT, enabling intelligent and remote temperature and lighting control to yield energy-saving gains. The rise of IoT relies heavily on the growth of several allied technology advances, including ultra-low-power microcontrollers, low-power wide area networks (LPWANs), and the increasing use of edge-based machine learning algorithms. However, one crucial and essential requirement for any IoT sensor or actuator, no matter how small or large, is access to a sustainable and reliable energy source.

Powering an IoT Device

Engineers have several choices when powering an IoT device. First is line power, but access to line power cannot always be ensured. Additionally, installing line power to every device, particularly across a large-scale deployment, can be prohibitively expensive, as is the case for provisioning wired network communications.

Using a primary battery is an ideal alternative to line power. The availability of low-power microcontrollers greatly eases the power consumption requirements, making a battery viable. However, depending on the estimated battery life, the device will require regular and costly service calls to replace it. Having a rechargeable battery or using a supercapacitor as energy storage offers possible solutions, but it still needs a source of energy to keep it charged.^[1]

The last decade has seen considerable advances in reducing the power profile requirements of microcontrollers and associated hardware. The amount of power involved means that methods of energy creation that were previously considered unable to deliver sufficient power are now viable.

The ability to harvest energy from ambient sources has existed for decades, with solar and wind being the most prolific, particularly for large-scale energy farms. However, those and other methods lend themselves to harvesting the minute amounts of energy sufficient to meet the needs of IoT devices.

Using a suitable energy storage medium with energy harvesting, careful power management, the energy-efficient use of microcontroller sleep modes, and low-duty cycle tasking provide an excellent method for accelerating IoT deployment.

Energy Harvesting and Storage Techniques

Many energy harvesting methods suit IoT use cases, but not all are appropriate for every application. For example, solar is best suited for outdoor environments where regular exposure to the sun is possible. However, new harvester technologies that work with low-lumen indoor light sources are currently under development.

For each harvesting technique listed in Table 1, design engineers should also consider the physical constraints (e.g., size, weight, IP rating) of the end IoT product, as well as its output voltage and energy harvesting capabilities.

Table 1. Power available from energy harvesting sources (Source: A Pop-Vadean, P P Pop, C Barz, and O Chiver. “Applications of Energy Harvesting for Ultralow Power Technology”)^[2]

Kinetic Energy Harvesting

Wind turbines are now a familiar sight in many countries, usually as part of large-scale wind farm installations. This form of kinetic energy harvesting, which turns rotational energy into electrical energy, is highly scalable. Small compact harvesters, placed to capture wind or water flow, offer a wide range of power outputs. Even a tiny dynamo harvester can generate more than enough energy for most practical IoT requirements.^[3] However, the size of the end device and potential safety concerns of moving parts may limit the use. That said, for some applications, designers may want to mount all the device's electronics inside the harvester's enclosure.

Vibration and Movement Harvesting

Vibration and movement energy harvesting are becoming extremely popular. The ability to harvest and store relatively small amounts of energy suits a wide range of IoT developments. Vibration may be caused by the regular operation of a motor, while movement harvesting may include using a sensor to convert the energy from pedestrians or vehicles crossing a bridge.

Examples of vibration harvesting techniques include:

• piezoelectric elements, which generate energy through mechanical stress;
• electrostatic elements, which use capacitive induction to produce small amounts of energy; and
• electromagnetic induction, which relies on the movement of a coil through a magnetic field to generate electricity.

Each technique has its merits, and the use case and the energy requirements will dictate which approach is optimal. For example, battery-less switches could use a piezoelectric technique, where the energy generated through the switch's clicking action is sufficient to power a wireless sensor node to control an operation. An industrial application could involve a vibration harvester used to power an IoT sensor monitoring a motor's state of health.

Solar

Solar power is an evergreen method of energy harvesting that has become even more popular recently with the availability of indoor ambient light energy harvesters. Solar harvester manufacturers have devised creative and flexible approaches that have moved away from traditional rectangular silicon-based photovoltaic (PV) panel shapes to those designed to fit around the customer's enclosure.^[4] New PV technologies, such as perovskite, promise to improve energy yields, particularly in the low-light, non-solar environments experienced in an office or industrial complex.

Thermoelectric

Thermoelectric energy harvesting employs the temperature difference between two semiconductor materials (known as the Seebeck effect) to generate electricity. A wide variety of thermal electric generator (TEG) modules are already available on the market. TEGs are ideal where a source of waste heat is regularly available. In practice, these tend to be limited to industrial processes. However, with a sufficient available temperature gradient and an appropriately sized module, they offer immense flexibility.

Ambient RF Energy Harvesting

As the power consumption profile of an IoT device falls, other harvesting technologies become viable. The concept of harvesting RF energy is relatively new but looks set to become a popular method. In this method, energy is harvested from a directed beam of an RF signal. Some applications, such as the smart product price labels on supermarket shelves, already use RF energy harvesting.

Ambient RF energy harvesting employs a fixed wireless transmitter and antenna to send energy to receiving devices. Harvesting ambient RF energy from the myriad sources surrounding us offers many possibilities. The RF spectrum around an office or home is typically awash with radio communication, from Wi-Fi^®, cellular, and Bluetooth^® technologies to industrial modules using ISM bands. For designers of IoT devices that can be deployed in a wide variety of locations, the challenge may be finding sufficient and sustainable amounts of RF energy to ensure continued operation.

System-Level Considerations

Harvesting energy from available sources adds flexibility and agility to any IoT device. However, design engineers must consider the actual energy available. How long can the IoT device maintain operation when the harvested energy falls below certain thresholds, such as during an overcast day at an outdoor solar energy farm?

Power profiling the device’s energy consumption is essential to any battery-powered embedded system. This involves carefully balancing the device’s operational duty cycle against the available energy through sleep modes and phasing power-hungry tasks. Energy harvesting ICs typically incorporate power management capabilities optimized for the harvester technology (Figure 1).

Figure 1: System-level diagram shows how the lifetime of a wireless sensor node (WSN) could be extended with energy harvesting. (Source: Mouser Electronics)

Depending on the use case and the power requirements, harvesting energy from multiple sources may provide redundancy. Some energy harvester ICs now support inputs from different harvesting elements and modules, while other ICs are agnostic of the harvester type, offering greater design flexibility across a product range.

Energy Harvesting Accelerates IoT Deployments

The IoT and IIoT rely on an army of sensors and actuators to monitor and control everything from office lighting to industrial production lines. Using energy harvesting to power an IoT device can significantly ease the deployment headaches associated with powering devices in locations where line power is unavailable or too costly to install. It also offers more placement flexibility for devices in remote or hard-to-reach areas, such as when monitoring soil moisture levels across a large field or room occupancy sensors across a university campus.

Thanks to improvements in microcontroller efficiency and wireless technologies, even small amounts of harvested energy from light, vibration, temperature, or RF can be enough to keep an IoT device running reliably.

As energy harvesting technologies and materials like low-light PV, piezoelectric elements, and RF harvesters continue to expand, engineers now have powerful tools to extend battery life or even eliminate batteries.

Sources

[1]https://resources.mouser.com/energy-harvesting/supercapacitors-find-applications-in-hybrid-vehicles-smartphones-and-energy-harvesting
[2]https://doi.org/10.1088/1757-899X/85/1/012024
[3]https://doi.org/10.1109/WIECON-ECE64149.2024.10915086
[4]https://resources.mouser.com/explore-all/latest-solar-panel-technology-shines-bright